docs: def on_deckbuilder(self, *args):
          """Bind my deckbuilder to update my ``scroll``, and my ``scroll`` to
          update my deckbuilder.
  
          """
          if self.deckbuilder is None:
              return
          att = 'deck_{}_hint_offsets'.format(
              'x' if self.orientation == 'horizontal' else 'y'
          )
          offs = getattr(self.deckbuilder, att)
          if len(offs) <= self.deckidx:
              Clock.schedule_once(self.on_deckbuilder, 0)
              return
          self.bind(scroll=self.handle_scroll)
          self.deckbuilder.bind(**{att: self.upd_scroll})
          self.upd_scroll()
          self.deckbuilder._trigger_layout()